1. Field of the Invention (Technical Field)
The present invention relates to pool table or billiard table slate lifters and to the methods of using such lifters.
2. Background Art
Pool and billiard tables are comprised of two main components: a cabinet housing and a slate which forms the actual playing surface. A slate is a unitary, typically rectangular, planar material that is usually composed of a very dense, heavy material. The weight of the slate often causes a structural creep with in the cabinet (sag). Additionally, general use of the table results in wear of a fabric covering the slate. As a result repairs are periodically needed to the table to place shim materials on the various slate supports to accommodate for the sag. Removal of the fabric covering for replacement is also periodically required. These periodic repairs are very difficult to accomplish given the weight and unwieldiness of the slate. In the past, removal of a slate could only be accomplished with the combined manpower of two or more people. The present invention can be used by a single person and does not require the user to exert a great deal of physical force in its operation.
Other than the unwieldy nature of the slate, the slate's configuration and composition presented additional concerns for its manipulation. If any structural deficiencies are present in the slate, the pressures applied by lifting the slate at one point, especially on an angle and on only one side, can result in the cracking or breaking of the slate. Prior art slate lifters such as the device disclosed in U.S. Pat. No. 5,340,083 to Suhy et al., utilize a jack type apparatus that is inserted at one point under the slate and is used to lift the slate from one side. Therefore, the slate is lifted on an angle with the non-lifted side bracing against the cabinet. This type of device is not best suited for lifting a large, heavy planar material such as a slate since the forces exerted at the single lift point could stress the slate resulting in cracking or breaking. The present invention utilizes multiple lift points on opposing sides of the slate thereby minimizing stress to the slate.
The '083 patent device, while accomplishing lift, is unsuitable to allow a single user to lift a slate entirely. The device utilizes only one lift point, requiring the user to operate the device on one side of the table at a time. The slate is lifted and whatever repairs are possible are performed on the lifted side. The slate is then lowered, and the device is disengaged. The device is then moved to the opposite side of the table, and the process begins again. This is a time consuming inconvenience that is avoided by the present invention.
Further, the '083 device, which braces one edge of the slate against the table while lifting the opposing side, may shift at its brace points, requiring the user to hold the slate at all times to prevent slipping. The present invention provides a mechanism that does not require the user to hold the slate in place to prevent possible “slips” that could harm the slate, the table, or the user.
Lifting devices for slabs that are not specifically designed for pool table slates are known in the art. U.S. Pat. No. 4,962,913 to Stewart discloses a device for lifting sidewalk slabs for repair. The device comprises a rigid longitudinal span supported over the sidewalk with cross members. Winches are employed on the cross members to raise hooks disposed on cables. The '913 patent discloses separate winches for each cross member without interrelation other than potentially utilizing adjacent switch operation of each winch or providing a master control switch. Such adjacent switches or even a master switch cannot ensure synchronous, concurrent operation of the winches. As a result, the slab will not be maintained in a horizontal position throughout the lifting process. This destabilizes the load, introducing the potential for loss of the load during the lifting process. The lifting mechanism of the present invention overcomes this problem.